Electric-arc lamp



(No Model.)

J. A. MGSHER.

vELECTRIC ARC LAMP.

N6. 644,666. Patented Aug. 6, 1696.

lilill!! if# UNITED STATES PATENT OFFICE..

JOHN A. IvIosIIER, OE OI-IIcAeo, ILLINOIS.

ELECTRIC-ARC LAM P.

SPECIFICATION forming part of Letters Patent No. 544,066, dated August 6,- 1895.

Application tiled May 11, 1395. Serial No. 548,942. (No model.)

To all whom it may concern.-

Beit known that I, JOHN A. MOSHER, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Arc Lamps; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

The invention relates to alternating-current arc lamps, its object being to provide a lamp which may be operated without the use of a delicate feed mechanism, which shall be noiseless bothl in its mechanism and at its are, which will give a uniform candle-power, which will be economical both of manufacture and of current, and which shall be complete within itself, adapting a current of high electromotive force to its own requirements without the need of independent accessory transforming apparatus.

The invention consists in so mounting a pair of carbon electrodes that they approach each other by the action of gravity and are held in continuous contact, the arc being formed around the point of contact, and in combining with a pair of carbons so mounted a transforming agent 'situated within the frame of the lamp and having its secondary circuit comprised wholly within the lamp, such. transformer being adapted to adjust a current of high potential to the requirements of the lamp. An arc is formed when the carbons are in continuous contact by the employment of a large volume of current with little force. The currentl meets with sufficient resistance at the point of contact to develop a destructive temperature. The combustion of the carbons supplies in the gases developed the medium for carrying the arc, so that, whilea small part ofthe current finds a path through the points in direct contact, much of it crosses the space between the carbons in the form of an annular or barrel shaped are, within which may be seen the carbons heated to incandescence. The arc causes the destruction of the carbons around the points and retards it directly at the points by excluding the air. As a result the carbon assumes a sharply-pointed form, the two carbons seeming to become united by a small neck whichgradually crumbles, and .the little weight applied causes the carbons to approach as this destruction proceeds. 'The arc thus produced and main tained, when'produced by acurrent of proper volume and electromotive force, is highly efcient and is free from the many and serious objections that have been present in all lamps supplied with alternating currents thus far produced. Absolutely no noise is produced either in the feed mechanism or at the arc itself.

It is well known that the hum of the arc of an alternating lamp renders its use in many cases impossible, and wherever used it is extremely objectionable; while the use of an electromagnet with a movable armature for controlling the feed of the carbons involves a v Dispensing entirely with the delicate feed l mechanism I am able to reduce the cost of manufacture and to wholly escape the disadvantages above indicated attending the use of such adj uvncts.

The freedom from noise at the arc is dueto the different conditions under which the arc is formed. It is found in practice that even with the low voltage employed in this lamp an arc can be formed if the carbons be slightly separated, yet with the slightest separation of the carbons the hum is set up.

The difficulties encountered in utilizing the arc now described arise from the peculiar nature of the current required as compared with that used in producing an arc between separated electrodes, the amprage being in creased many fold and the voltage reduced to a greater degree. It is obvious that it is impracticable to convey such a current to the lamp even a short distance, the size of the wire necessary being too great. I have there- IOO with a current practicable of transmission and will itself transform this current to meet its own requirements.

A further advantage arising from the form of lamp now described is found in the reduced cost of carbons. lVith the high Voltage nec cessary in the old style of lamps carbons of superior quality were required to prevent heating back from the points. The low voltage I employ in my improved lamp will be carried as well by carbons of very inferior grade and consequently low price.

In the drawing, I show a diagrammatical figure which I believe to be sufficient to a full understanding of the construction and arrangement of the lamp.

The carbons are indicated at A B, and the carbon-holders at a l). These holders are sus pended from opposite ends of a cable C, which is hung over a sheave D, which may be journaled in any desired manner in the ordinary form of frame of an are lamp. Gravity is depended upon for feed, the holder a being sufficiently heavy to outweigh the holder b, so that as the carbone are consumed the upper one descends and the lower one rises. The counterweighting is so adjusted as to insure a gentle contact of the carbon points continu ously.

The two wires of the main line are indicated at E F, and they lead to opposite ends of the coil of an electromagnet G, which is located within the head of the lamp and Which may beof any desired form.

The wires of the lamp-circuit are indicated at II J, the former leading to the lower and the latter to the upper carbon. Both wires of thelamp-circuit are brought into electrical connection with the main line, the wire I'I being connected with one of the wires, as E, preferably at its juncture with themagnet, as indicated at 7L, and the wire J being connected with one of the intermediate convolutions of the coil of the electromagnet, as indicated at j. The convolutions of the coil of the magnet lying between the points hj are therefore common to both circuits and are formed of a wire of sufficient size to have the capacity to carry the current used upon the la1np-circuit.

The electromagnet is so proportioned that the counter electromotive force developed by it in the main line is approximately equal to .the electromotive force ofthe service current.

The servicecurrent tinds an easier path through the lamp than through that portion of the magnet between the points 71j. Its passage through the remainder of its coil induces a current in the opposite direction in the lamp-circuit proportionate with the number of turns of the latter about the magnet. While the service-current has its electromotive force practically reduced to m'l, the desiredjvoltage is secured from the induced current. The entire volume of the servicecurrent passes through the lamp and is supplemented by the volume of the induced current, which is measured by the consumption of force necessary to drive the servicecur rent through the magnet. By this arrangement, therefore, the lamp is provided with the large current required in its class and relieved of the high electromotive force, without necessitating the use of a large wrein the linefcircuit which a current of great volume would require, thereby rendering the lamp commercially practicable.

I claim as my invention- 1. In an arc lamp the combination with a service electric circuit leading to the lamp, and with an electro-magnet Gr, within the lamp, and whose coil is included within the service circuit, of a second electric circuit comprised within the lamp, and being wound upon the magnet G, and electrically connected with the service circuit at one side of the magnet and also intermediate of the ends of the magnet, anda pair of mutually approach ing carbone forming a part of the lamp circuit and having their points continuously in contact.

2. As an article of manufacture an are lamp comprising a frame, a transforming agent carried by the frame and having its secondary circuit wholl y within the lamp, and a pair of movable electrodes forming a part of the secondary circuit and means for main taining the electrodes in continuous contact, substantially as described and for the purpose specilied.

In witness whereof I have affixed my signature in the presence of two witnesses.

JOHN A. MOSIII t.

Witnesses:

Louis K. GILLsoN, W. T. BAR'rnoLorntw.

IOO 

